The present invention relates to the area of agricultural soil working and product application and, more particularly, to a guidance system and display to enable optimally driving swaths in rectangular fields, where parallel swathing is most efficient, and odd shaped fields, where contour swathing is more desirably employed.
As agricultural tractors have increased in size and horsepower, agricultural implements for cultivating soil and for applying treatment products, such as fertilizers, herbicides, insecticides, or the like, to soil and crops have also progressed from those which worked a single crop row to those which may work tens of rows simultaneously. The reasons for such growth in agricultural equipment include efforts to increase productivity through increases in fuel efficiency and decreases in time required to work a given field. Thus, it is advantageous to combine numerous agricultural operations per pass and to maximize the swath or soil working path width per pass. Another factor which affects productivity is crop yield per unit of field area. For this reason, it is desirable to maximize the percentage of arable land which is cultivated by avoiding gaps. At the same time, it is desirable to avoid overlapping cultivation which wastes resources.
The cultivation of long straight, or parallel, crop rows is generally preferred since long rows minimize the number of turnarounds at the ends of rows, and parallel rows are relatively easy to drive accurately by the tractor operator. Flat fields with straight boundaries are especially suited to parallel crop rows. Fields with a more xe2x80x9chillyxe2x80x9d character benefit from contour plowing in which the crop rows extend generally perpendicular to the gradient of the ground surface. Contour rows maximize moisture retention and minimize soil erosion. Also, contour rows are sometimes preferred for fields with irregular boundaries.
Parallel rows are easier to cultivate than contoured rows, and crop rows are more accurately worked with a narrow implement frame than a wide frame. In order to increase accuracy in cultivation, various practices have evolved to avoid gaps in cultivation and overlapping cultivation. Earliest practices included marking the edge of a xe2x80x9cswathxe2x80x9d in which an inert marking material is deposited during one pass from one extremity of the tool frame. On the next pass, the operator would attempt to align an outer extremity of the frame with the previously marked line. Although generally successful, marking methods involve an additional expense for the marking material and additionally the need to monitor the amount of marking material on-board and replenish when exhausted.
More recently, cultivation or swathing guidance has incorporated position data derived from satellite based global positioning systems. With current enhancements to the original GPS system, spatial resolutions of less than a meter are now possible. In general, GPS techniques have been applied to swath guidance in such a manner as to store data defining a desired path, detect current position and sometimes heading, calculate a position offset or heading error, and display a complement or opposite of the error to thereby guide the operator in maintaining the desired path or returning to the desired path. In practice, it has been found that such an approach tends to cause the operator to overshoot the correction, resulting in oscillation about the desired path. Such overshooting and oscillation is also found in application of an error signal in such a manner to an automatic steering mechanism. What is needed is a position detecting guidance approach which tends to lead the vehicle back onto the correct path without overshoot. Such a guidance method should also be applicable to both parallel cultivation as well as contour cultivation.
The present invention provides an improved system for vehicle guidance which is particularly well adapted for use in swathing guidance. The present invention includes a position detecting subsystem which provides data defining a currently detected position and a guidance controller which stores the positions detected by the position detecting system and is programmed with routines for generating and storing data defining a reference path and a current path, for calculating current speed and heading and an error in the current position, and for calculating a correction in heading to most expeditiously return the vehicle to the correct current path.
More specifically, the present invention repeatedly selects a future intercept point on the desired path and calculates a heading correction to cause the vehicle to move toward the intercept point. The cycle of selecting a new intercept point and heading correction is updated often enough to cause the vehicle, if off-track, to xe2x80x9cflarexe2x80x9d into the desired path. If the vehicle is already on the desired path or on a heading directly toward the intercept point, the method causes the vehicle to remain on the current heading.
In one embodiment of the invention, the apparatus includes a display including an arcuate array of steering indicators forming a steering guide along with a linear array of current position indicators to show relative distance and sense, or-relative direction, from the desired path. In another embodiment of the present invention, a steering correction signal is applied to an automatic steering mechanism on the vehicle to automatically correct or maintain the vehicle on the desired path.
Another embodiment of the invention uses two straight LED arrays for the steering error and cross track displays and seven-segment or alphanumeric displays for the menu and remote user entry through switches or a keypad.
The present invention makes use of automatic position detection technologies, preferably including a satellite based global positioning system, such as the United States developed Navstar system, and enhancements thereof. Current versions of differential GPS systems are known to have accuracies within less than one meter. Additionally, other types of position reckoning systems are known, such as those employing various kinds of odometers and rotation encoders, laser devices, and the like, as well as conventional swath marking systems. The present invention contemplates incorporation of such other positioning determining systems within the novel methods described herein.
The principal objects of the present invention are: to provide an improved system for vehicle guidance; to provide such a system which employs position detecting technique, such as by reception of signals from a satellite based global positioning system; to provide such a system which is particularly well adapted for ground working vehicle, such as agricultural vehicles for soil working, fertilizing, spraying, irrigating, harvesting, and the like; to provide such a system which minimizes gaps and overlaps in crop cultivation; to provide such a system which calculates data defining desired paths of the vehicle, monitors the current position of the vehicle in relation to a desired path, and generates a steering correction signal to maintain the vehicle on the path or to return the vehicle to the path; to provide such a system into which the implement width can be entered to enable calculation of the desired paths for the vehicle to follow; to provide such a system including a display device responsive to the steering correction signal for displaying a needed steering correction for manual steering control; to provide such a system in which the steering correction signal is applied to an automatic steering mechanism; to provide such a system which minimizes overshoot in correcting the track of the vehicle to the desired path; to provide, particularly, a system which repeatedly selects a future intercept point and generates the steering correction signal to cause the vehicle to move toward the intercept point; to provide such a system which is adapted for guidance during parallel swathing and additionally for contour swathing; to provide such a system which can be conveniently be retrofitted to existing tractors and vehicles; to provide such a system which can track and store data defining portions of a field worked, allowing an operator to resume accurate working of a field following an interruption; and to provide such a system which is economical to manufacture, which is accurate and efficient in operation, and which is particularly well adapted for its intended purpose.
Other objects and advantages of this invention will become apparent from the following description taken in relation to the accompanying drawings wherein are set forth, by way of illustration and example, certain embodiments of this invention.